TW201925082A - A method for producing spherical silicon nitride powder using carbothermal reduction nitridation reaction to reduce an occurrence of excessive carbon residues - Google Patents

Abstract

A method for producing a spherical silicon nitride powder, the steps comprising: (A) providing a silicon oxide powder and a carbon source, dispersing and dissolving the silicon oxide powder and the carbon source in a solvent to form a mixed slurry; (B) spray-granulating the mixed slurry to form a spherical powder; (C) carbonizing the spherical powder in a nitrogen atmosphere to form a carbonized spherical powder; (D) subjecting the carbonized spherical powder to a carbothermal reduction nitridation reaction under a nitrogen gas atmosphere to form a spherical silicon nitride powder; and (E) decarburizing the spherical silicon nitride powder in the atmosphere to form a spherical silicon nitride powder with high purity. By combining the steps of raw material mixing, spray granulation, carbonization treatment, carbothermal reduction nitridation reaction, decarburization and the likes, the spherical structure of the silicon nitride powder produced by the present invention has better powder fluidity and the compactness and true density of the block material after the molding process is improved.

Description

Method for preparing spherical tantalum nitride powder

The present invention relates to a method for preparing a tantalum nitride powder, and more particularly to a method for preparing a spherical tantalum nitride powder.

Niobium nitride is mainly used in high-temperature structural materials. It has excellent high-temperature strength, and has the characteristics of heat resistance, corrosion resistance, wear resistance, shock resistance, and mechanical strength comparable to metal materials. It is also a high performance. Electrically insulating materials have great potential for development in cutting tools, ceramic bearings, refractory materials, high frequency components and semiconductor applications.

Cerium nitride exists in both crystalline forms of alpha and beta phases, all of which belong to the hexagonal system and have similar unit cells. In general, α-phase tantalum nitride is unstable and often contains trace amounts of oxygen. The empirical formula is Si ₁₂ N ₁₅ O _0.5 , while the β-phase tantalum nitride is higher temperature and low oxygen partial pressure. The product, when the temperature exceeds 1650 ° C, α-phase tantalum nitride will be directly transformed into columnar β-phase grains with high aspect ratio, and the heterogeneous distribution of such grains can lead to crack turning and bridging. The tantalum nitride sintered body has a main cause of high strength and high toughness. The theoretical density values of the α phase and the β phase are 3.18 and 3.19 g/cm ³ , respectively, and the tantalum nitride undergoes significant thermal decomposition at about 1800 ° C under a nitrogen atmosphere of one atmosphere, and in the atmosphere or higher oxygen. In a partial pressure environment, tantalum nitride forms a protective layer of cerium oxide on its surface and inhibits the oxidation reaction.

There are several methods commonly used in the industrial preparation of tantalum nitride powder: direct nitridation, chemical vapor deposition, and imide thermal decomposition. Combustion synthesis, Carbothermal reduction, etc. The main way to produce tantalum nitride powder in the industry is to use a carbothermal reduction method, which mainly involves solid phase mixing of cerium oxide or cerium oxide powder with a carbon source, and powdering using a high temperature furnace under a nitrogen or ammonia atmosphere. The sintering process uses a carbon source for the reduction reaction, and the powder prepared by the method has the advantages of fine powder, uniform particle size, high product purity and mass production, and therefore is directly produced by the direct nitriding method of bismuth powder. The main mode of the tantalum nitride powder is as follows: nitrogen: 3SiO _{2 (s)} + 6C _(s) + 2N _{2 (g)} → Si ₃ N _{4 (s)} + 6CO _(g)

Ammonia: 3SiO _2(s) +6C _(s) +4NH _3(g) → Si ₃ N _4(s) +6CO _(g) +6H _2(g)

Zhong Xianlong et al., "Method for manufacturing high specific surface area α phase tantalum nitride powder" (Patent No.: I347299), first using NH ₄ NO ₃ as an oxidant and using glycine (aminoacetic acid) and urea (urea) as The fuel is subjected to a solution combustion synthesis method to prepare a reaction precursor powder (SiO ₂ + C). Since the ratio of carbon to cerium oxide is low in the reaction precursor, extra sucrose is added as a carbon source, and finally the obtained The precursor is subjected to a hot carbon reduction nitridation reaction in a tubular high-temperature furnace in a nitrogen atmosphere to obtain a high specific surface area α phase tantalum nitride powder. Chai Tian Gengsi et al., "Method for producing tantalum nitride powder and tantalum nitride powder, and tantalum nitride sintered body and circuit board using the same" (Patent No. I573757), silicon diimide And a nitrogen-containing decane compound such as silicon tetramide or silicon chloroimide is thermally decomposed to obtain an amorphous Si-NH compound, which is placed in a continuous sintering furnace to be in a flowing state. The sintering process is carried out at a temperature of 1400 to 1700 ° C in a nitrogen atmosphere to obtain a tantalum nitride powder having less internal oxygen and having surface oxygen suitable for sintering. Crosbie's invention patent "Method of making a special purity silicon nitride powder" (Patent No.: US 4582696), after the combustion of Tetraethyl orthosilicate and ammonia gas to produce amorphous tantalum powder and carbon black The carbothermal reduction nitridation reaction is carried out in a nitrogen atmosphere at 1300 to 1500 ° C to obtain a high-purity α phase tantalum nitride powder. Schroll's invention patent "Method for producing high-purity silicon nitride" (Patent No.: US 8697023B2), which places high-purity tantalum powder into a rotary tubular high-temperature furnace by regulating the mixing of three gases, such as nitrogen, argon and hydrogen. In the ratio, the sintering process is completed at 1100 to 1450 ° C to complete the nitriding reaction, and a high-purity tantalum nitride powder can be obtained.

Therefore, at present, most of the methods for synthesizing tantalum nitride powder are direct nitridation and carbothermal reduction. However, the direct nitridation method is time consuming and energy consuming. The carbothermal reduction method mainly mixes the cerium oxide powder with carbon black, and performs the carbothermal reduction nitridation reaction under a nitrogen atmosphere at 1500 ° C, but the cerium oxide powder and It is difficult to achieve homogeneous mixing of carbon black, which will cause the problem of incomplete carbon reduction and nitriding of the powder and excessive carbon residue, which will increase the time of the subsequent carbon removal process, increase the oxygen content of the tantalum nitride, and reduce the nitrogen. The purity of the bismuth powder affects the quality of the subsequent block forming With reliability. Moreover, the tantalum nitride powder of the conventional preparation method has an irregular shape, the particle diameter has a distribution range, and the fluidity is poor, and the inter-particle chain is likely to cause void defects in the subsequent mold-forming type and sintering reaction, which affects the compactness of the block and True density.

Therefore, there is a need in the industry for a method for preparing a spherical tantalum nitride powder, which can uniformly mix the cerium oxide powder with a carbon source, and has no problem of excessive carbon residue in the carbothermal reduction nitriding reaction, and is simple and time-saving. In addition to the carbon process, a spherical tantalum nitride powder having a uniform particle size in accordance with industry requirements is prepared.

In view of the above disadvantages of the prior art, the main object of the present invention is to provide a method for preparing a spherical tantalum nitride powder, which can be prepared by mixing raw materials, spray drying, carbonization, carbothermal reduction, nitriding and carbon removal. A spherical tantalum nitride powder having good characteristics.

In order to achieve the above object, according to one aspect of the present invention, a method for preparing a spherical tantalum nitride powder is provided, the steps comprising: (A) providing a cerium oxide powder and a carbon source, the cerium oxide powder And the carbon source is dispersed and dissolved in a solvent to form a mixed slurry; (B) the mixed slurry is spray granulated to form a spherical powder; (C) the spherical powder is subjected to a nitrogen atmosphere Carbonization treatment to form a carbonized spherical powder; (D) subjecting the carbonized spherical powder to a carbothermal reduction nitridation reaction under a nitrogen atmosphere to form a spherical tantalum nitride powder; (E) the spherical tantalum nitride The powder is decarburized in the atmosphere to form a high-purity spherical tantalum nitride powder.

The carbon source of the above step (A) is selected from the group consisting of glucose, sucrose or phenolic One of the resins; the weight ratio of the cerium oxide powder to the carbon source is 1:1.0-2.5, wherein the weight ratio of the cerium oxide powder to glucose may be 1:2.5, the cerium oxide powder The weight ratio of the body to the sucrose may be 1:2.0, the weight ratio of the cerium oxide powder to the phenolic resin may be 1:1.0; the solvent is selected from one of water or ethanol; the cerium oxide powder The solid content of the mixed slurry is between 10 and 20% by weight to adjust the viscosity of the mixed slurry to be about 50 cP (centipoise); the mixing method may be ball milling, and the ball milling method may be a planetary ball mill. In the invention, the easily obtained carbon material is used as the carbon source of the sintering reaction, and the planetary ball mill can be used for the high energy homogeneous mixed carbon source, the solvent and the nanometer cerium oxide powder, and the ball beads of different particle sizes are repeatedly used for high energy. The ball milling process is formulated to produce a spray granulation slurry of optimum viscosity.

The above step (B) is carried out by a spray granulation process to complete the uniform coating of the cerium oxide powder by the micronized carbon source, and the optimum weight ratio of the cerium oxide powder to the carbon source is 1:1.0-2.5. A spherical cerium oxide powder uniformly coated with a carbon source is prepared, and the particle size is about 40 to 50 μm.

The carbonization treatment temperature in the above step (C) is from 700 ° C to 800 ° C; and the carbothermal reduction nitridation reaction temperature in the step (D) is from 1400 ° C to 1500 ° C, preferably from 1450 ° C.

In the above step (E), the spherical tantalum nitride powder may be placed in a rotating high temperature furnace to perform a homogeneous carbon removal process under the atmosphere; the carbon removal temperature is 700 ° C to 800 ° C.

The invention adopts a spray granulation process to convert the starting material cerium oxide with The mixed slurry of carbon source is atomized at a high temperature (60 rpm or more) in a set temperature range of 60 ° C to 200 ° C to produce a dry spherical solid powder. This method not only has a fast drying process, but also directly controls spherical powder particles. The diameter is 40~50μm. In addition, the carbonization, carbothermal reduction and nitridation reactions can be completed at one time by changing the temperature rise curve parameters of the high-temperature sintering process to prepare a high-purity spherical tantalum nitride powder.

The invention is a method for preparing a spherical tantalum nitride powder. The method is characterized in that the easily obtained carbon source and the ceria powder are spray-dried to carry out a spheroidizing granulation process to obtain a micron-sized spherical uniformly mixed powder. The carbon dioxide source is uniformly coated with the cerium oxide powder in the carbothermal reduction reaction, and the nitriding conversion rate under the nitrogen atmosphere sintering can be effectively improved to achieve the purpose of reducing the amount of the carbon source used, and the spherical structure of the cerium nitride powder The particle size is uniform, and the powder has good fluidity, which can improve the compactness and true density of the block after the mold is formed, and reduce the hole defects caused by the inter-particle chain during the sintering reaction, and subsequently develop the earthquake-resistant high pressure. The tantalum nitride substrate.

The above summary, the following detailed description and the accompanying drawings are intended to further illustrate the manner, the Other objects and advantages of the present invention will be described in the following description and drawings.

S101-S105‧‧‧Steps

The first figure is a flow chart of a method for preparing a spherical tantalum nitride powder according to the present invention; The second figure is a spherical powder scanning electron microscope spectrum after spray granulation according to an embodiment of the present invention; the third figure is a spherical tantalum nitride powder scanning electron after the carbothermal reduction nitridation reaction according to the embodiment of the present invention. Microscopic map; the fourth figure is a diffraction pattern of spherical tantalum nitride powder X-ray powder after the carbothermal reduction nitridation reaction of the embodiment of the present invention.

The embodiments of the present invention are described by way of specific examples, and those skilled in the art can readily appreciate the advantages and effects of the present invention from the disclosure herein.

The method for preparing the spherical tantalum nitride powder of the invention can be uniformly coated on the surface of the cerium oxide powder by a high-energy ball milling process and spray granulation, and uniformly mixed after one carbonization, at 1400. The sintering process is carried out under a nitrogen atmosphere of °C-1500 °C to complete the carbothermal reduction nitridation reaction to form a spherical tantalum nitride powder. The sintered powder can be placed in a rotating high temperature furnace under an oxygen atmosphere for a homogeneous carbon removal process. The preparation of high-purity spherical tantalum nitride powder is completed. The carbothermal reduction nitridation reaction is a carbon source component which is carbonized on the surface of the cerium oxide powder as a reducing agent, and the cerium oxide is reduced under a nitrogen atmosphere, and the reduced cerium reacts with nitrogen to form nitriding.矽 powder.

Please refer to the first figure, which is a flow chart of a method for preparing a spherical tantalum nitride powder according to the present invention. As shown in the figure, a method for preparing a spherical tantalum nitride powder according to the present invention comprises the steps of: (A) providing a cerium oxide powder and a carbon a source, the cerium oxide powder and the carbon source are dispersed and dissolved in a solvent to form a mixed slurry S101; (B) the mixed slurry is spray granulated to form a spherical powder S102; (C) The spherical powder is carbonized in a nitrogen atmosphere to form a carbonized spherical powder S103; (D) the carbonized spherical powder is subjected to a carbothermal reduction nitridation reaction under a nitrogen atmosphere to form a spherical tantalum nitride powder. The body S104; (E) the spherical tantalum nitride powder is decarburized under the atmosphere to form a high-purity spherical tantalum nitride powder S105.

Wherein, the carbon source is one selected from the group consisting of glucose, sucrose or phenolic resin; the solvent is selected from one of water or ethanol; and the weight ratio of the cerium oxide powder to the carbon source is 1 : 1.0-2.5; the solid content of the cerium oxide powder in the mixed slurry is between 10 and 20% by weight; the mixing method may be ball milling.

Example 1: 75 g of glucose was dissolved in 1500 mL of deionized water, and then 30 g of cerium oxide powder was added, and the ball milling beads of different particle diameters were repeatedly subjected to a high-energy ball milling process to form a uniformly mixed spray granulation slurry. The mixed slurry was spray-dried at a nebulizer rotation speed of 15000 rpm, a circulating fan frequency control of 40 Hz, an inlet temperature setting of 160 ° C, an outlet temperature setting of 100 ° C, and a feed rate control of 20 ml/min to form a micronized carbon. The source uniformly coats the spherical powder of cerium oxide. Please refer to the second figure, which is a scanning electron micrograph of a spherical powder after a spray granulation process according to an embodiment of the present invention. As shown in the figure, the powder after spray drying exhibits a spherical shape, and the average of the powder is measured. The particle size was 45.36 μm. The obtained spherical powder is placed in BN坩埚 (boron nitride) The sintering process is carried out, and the carbonization treatment is carried out in a high-temperature furnace at 800 ° C in a nitrogen atmosphere, and the carbonization time is 2 hours to form a carbonized spherical powder. The carbonized spherical powder is further heated to a temperature of 5 ° C / min to 1450 ° C, and held for 5 hours, and subjected to a carbothermal reduction nitridation reaction in a high temperature furnace under a nitrogen atmosphere to form a spherical tantalum nitride powder. body. Please refer to the third figure, which is a scanning electron microscope image of the spherical tantalum nitride powder after the carbothermal reduction nitridation reaction according to the embodiment of the present invention. As shown in the figure, the powder after the carbothermal reduction nitridation reaction has a spherical shape. And has a hole structure. Finally, a high-purity spherical tantalum nitride powder was prepared by rotating the sintered tantalum nitride powder at 800 ° C for 10 hours in a homogenizing carbon removal process. Please refer to the fourth figure, which is a diffraction pattern of the spherical tantalum nitride powder X-ray powder after the carbothermal reduction nitridation reaction according to the embodiment of the present invention, and the weight ratio of cerium oxide to glucose is 1:2.5. It is shown that the prepared powder exhibits a tantalum nitride α crystal phase, and it has been confirmed that a spherical tantalum nitride powder has been prepared.

Example 2: 60 g of sucrose is first dissolved in 1500 mL of deionized water, and then 30 g of cerium oxide powder is added, and ball milling beads of different particle sizes are repeatedly used for high-energy ball milling to form a uniform mixed spray granulation. Slurry, the mixed slurry is controlled at a rotation speed of 15000 rpm, a cycle fan frequency control of 40 Hz, an inlet temperature setting of 180 ° C, an outlet temperature setting of 100 ° C, and a feed rate control of 20 ml/min for a spray drying process to form a micronized carbon. The spherical powder of the cerium oxide was uniformly coated with the source, and the average particle diameter of the powder was measured to be 43.27 μm. The obtained spherical powder is placed in BN坩埚 (boron nitride) for sintering process, and carbonization is carried out in a high-temperature furnace at 800 ° C in a nitrogen atmosphere, and the carbonization time is performed. For 2 hours, a carbonized spherical powder was formed. The carbonized spherical powder is further heated to a temperature of 5 ° C / min to 1450 ° C, and held for 5 hours, and subjected to a carbothermal reduction nitridation reaction in a high temperature furnace under a nitrogen atmosphere to form a spherical tantalum nitride powder. body. Finally, a high-purity spherical tantalum nitride powder was prepared by rotating the sintered tantalum nitride powder at 800 ° C for 10 hours in a homogenizing carbon removal process. Please refer to the fourth figure, which is a diffraction pattern of the spherical tantalum nitride powder X-ray powder after the carbothermal reduction nitridation reaction according to the embodiment of the present invention, and the weight ratio of cerium oxide to sucrose is 1:2.0, as shown in the figure. It is shown that the prepared powder exhibits a tantalum nitride α crystal phase, and it has been confirmed that a spherical tantalum nitride powder has been prepared.

Example 3: 30 g of phenolic resin was dissolved in 1000 mL of ethanol, and 30 g of cerium oxide powder was added, and the ball milling beads of different particle sizes were repeatedly used for high-energy ball milling to form a uniform mixed spray granulation slurry. The slurry was spray-dried at a nebulizer speed of 15,000 rpm, a circulating fan frequency of 40 Hz, an inlet temperature of 100 ° C, an outlet temperature of 80 ° C, and a feed rate of 20 ml/min to form a micronized carbon source. The spherical powder of the cerium oxide was uniformly coated, and the average particle diameter of the powder was measured to be 46.21 μm. The obtained spherical powder was placed in a BN bismuth (boron nitride) for sintering process, and carbonized at a high temperature furnace at 800 ° C in a nitrogen atmosphere for a carbonization time of 2 hours to form a carbonized spherical powder. The carbonized spherical powder is further heated to a temperature of 5 ° C / min to 1450 ° C, and held for 5 hours, and subjected to a carbothermal reduction nitridation reaction in a high temperature furnace under a nitrogen atmosphere to form a spherical tantalum nitride powder. body. Finally, the sintered tantalum nitride powder is sintered at 800 ° C using a rotating high temperature furnace. The high-purity spherical tantalum nitride powder was prepared by performing a 10-hour homogeneous carbon removal process. Please refer to the fourth figure, which is a diffraction pattern of the spherical tantalum nitride powder X-ray powder after the carbothermal reduction nitridation reaction according to the embodiment of the present invention, and the weight ratio of the cerium oxide to the phenolic resin is 1:1.0, as shown in the figure. As shown, the prepared powder exhibited a tantalum nitride α crystal phase, and it was confirmed that a spherical tantalum nitride powder had been prepared.

The present invention uses a spray granulation combined with a carbothermal reduction nitridation method to prepare a spherical tantalum nitride powder. Compared with the conventional carbothermal reduction nitridation method, the present invention uses glucose/sucrose/phenolic resin instead of carbon black as a carbon source. The spherical powder can be prepared by the spray granulation process as an adhesive, and the carbonization, carbothermal reduction and nitridation reaction can be completed once by changing the temperature profile of the high-temperature sintering, and the temperature can be in the range of 1400 ° C - 1500 ° C. Synthesis of tantalum nitride powder. The tantalum nitride powder with spherical structure has better powder fluidity, can improve the compactness and true density of the block after the mold is formed, and reduce the hole defects caused by the inter-particle chain during the sintering reaction. A highly reliable tantalum nitride substrate. Therefore, the invention has the advantages of simple process, no need to use additional adhesive, low production cost, reduced use of carbon source, etc., and has economic and energy-saving benefits, and can be introduced into domestic semiconductor, power components, automotive electronics and other application fields. It can effectively improve the service life and reliability of components in harsh environments such as high temperature, vibration and dust, making it more widely used in future applications.

The above-described embodiments are merely illustrative of the features and effects of the present invention and are not intended to limit the scope of the technical scope of the present invention. Anyone familiar with the art can implement the above without violating the spirit and scope of the invention. Examples are modifications and changes. Therefore, the scope of protection of the present invention should be as set forth in the scope of the claims described below.

Claims (13)

A method for preparing a spherical tantalum nitride powder, the method comprising: (A) providing a cerium oxide powder and a carbon source, dispersing and dissolving the cerium oxide powder and the carbon source in a solvent to form a mixture (B) spray-granulating the mixed slurry to form a spherical powder; (C) carbonizing the spherical powder under a nitrogen atmosphere to form a carbonized spherical powder; (D) The carbonized spherical powder is subjected to a carbothermal reduction nitridation reaction under a nitrogen atmosphere to form a spherical tantalum nitride powder; (E) the spherical tantalum nitride powder is decarbonized in the atmosphere to form a high-purity spherical nitrogen. Pupation powder. A method for preparing a spherical tantalum nitride powder according to claim 1, wherein the carbon source of the step (A) is one selected from the group consisting of glucose, sucrose or phenolic resin. A method for preparing a spherical tantalum nitride powder according to the first aspect of the invention, wherein the weight ratio of the cerium oxide powder to the carbon source in the step (A) is 1:1.0-2.5. A method for preparing a spherical tantalum nitride powder according to the second aspect of the invention, wherein the weight ratio of the cerium oxide powder to glucose in the step (A) is 1:2.5. A method for preparing a spherical tantalum nitride powder according to the second aspect of the invention, wherein the weight ratio of the cerium oxide powder to sucrose in the step (A) is 1:2.0. A method for preparing a spherical tantalum nitride powder according to the second aspect of the invention, wherein the weight ratio of the cerium oxide powder to the phenol resin in the step (A) is 1:1.0. A method for preparing a spherical tantalum nitride powder according to claim 1, wherein the solvent of the step (A) is one selected from the group consisting of water or ethanol. A method for preparing a spherical tantalum nitride powder according to claim 1, wherein the cerium oxide powder of the step (A) has a solid content of from 10 to 20% by weight based on the mixed slurry. A method for preparing a spherical tantalum nitride powder according to the first aspect of the invention, wherein the mixing method of the step (A) is ball milling. A method for preparing a spherical tantalum nitride powder according to claim 1, wherein the carbonization temperature of the step (C) is from 700 ° C to 800 ° C. A method for preparing a spherical tantalum nitride powder according to the first aspect of the invention, wherein the carbothermal reduction nitridation reaction temperature of the step (D) is from 1400 ° C to 1500 ° C. The method for preparing a spherical tantalum nitride powder according to the first aspect of the invention, wherein the step (E) is: placing the spherical tantalum nitride powder into a rotating high temperature furnace to perform homogeneous carbon removal in the atmosphere. Process. A method for preparing a spherical tantalum nitride powder according to the first or the twelfth aspect of the invention, wherein the carbon removal temperature of the step (E) is from 700 ° C to 800 ° C.